Improving Soil Health and Crop Productivity in Mississippi Utilizing Cover Crops and Poultry Litter

Dr. Jac J VarcoPlant and Soil Sciences Dept., Mississippi State University

North Mississippi Fruit and Vegetable Growers Conference February 8-9th

Objective

To determine the effects of mono- and bi-culture cover cropping with and without fall applied poultry litter on strip till corn productivity, N cycling, and soil quality and health indicators.

Methods

• Site Description – Alluvial soils mapped as a Marietta fine sandy loam (fine-loamy, siliceous, active, thermic Fluvaquentic Eutrudept) and Leeper silty clay loam (fine, smectitic, nonacid, thermic VerticEpiaquept).

• Experimental Design -Randomized complete block, four blocks with soil classification considered. Land planed for 1 to 2 % slope for furrow irrigation (rainfed only for study duration)

Methods cont.• Cover crops

1. Plant mid-late Oct. (Fall 2013 Leg=Hairy vetch (HV)/Crimson clover mix, rye, Leg-rye; Fall 2014-2015 Leg=HV, rye, Leg-rye; and Fall 2016 Leg=Persian clover, rye, Leg-rye)

2. Poultry litter application @ 2000 lb (dw basis) 3rd week of Nov. each year; source= Mighty-Grow

• Corn• Strip-tilled, rolled plots mid-April• Corn planted @32,000 kernels/acre

• Soil sampling• Enzyme assay (FDA); At planting (Day) , 14 DAP, and 28 DAP at 0- to 5-cm,

and 5- to 15-cm depths• Bulk density and total C and N analysis; post corn harvest;

CoverCrop/PL Cover Crop N Content, kg/ha

CC 2013 2014 2015 2016* 2017 Ave

Legume 91 96 60 14 64 65 (78)

Rye 50 33 29 24 44 36

LegRye 73 78 52 33 49 57 (63)

PL, Mg/ha

0 67 56 41 22 48 47

2 76 82 53 26 56 59

1. Cover crop N content prior to termination and corn planting

* Hairy vetch infested with root rot (Phytophthora sp.)

FDA Results, 2017

Days After Planting0 5 10 15 20 25 30

Enzy

me

Activ

ity, µ

g g-1

0

50

100

150

200

250

300

LSD=20.2

LSD=47.4NS

NS

NS

NS

FNRow

WF Row Leg Row Rye Row

LegRye Row FNMiddle WF Middle Leg Row Middle Rye Middle LegRye Middle

2. Microbial Activity-Fluorescein diacetate (FDA) hydrolysis

3. Soil bulk density 0- to 5-cm, fall 2016/2017

Treatment Row position

N rate (kg/ha) /CC/PL Row Inter-row

g/cm3

2016 2017 2016 2017

168/WF/No 1.36ab 1.36 1.38ab 1.38

Legume 1.36ab 1.30 1.44b 1.34

Rye 1.36ab 1.28 1.43ab 1.36

Leg-Rye 1.30ab 1.34 1.36ab 1.37

PL 1.30ab 1.29 1.42ab 1.34

Legume-PL 1.30ab 1.32 1.39ab 1.30

Rye-PL 1.28ab 1.25 1.35a 1.31

Leg-Rye-PL 1.27a 1.29 1.40ab 1.38

LSD(0.05) 0.10 0.09

Corn row vs. inter-row

Treatment Row Inter-row

N rate (kg/ha)/CC/PL Total N Total C Total N Total C

kg/m3

168/WF/No 1.17 14.1 1.38 17.3

0/Legume 1.26 14.5 1.62 19.3

0/Rye 1.25 14.6 1.52 18.4

0/Leg-Rye 1.26 14.5 1.61 19.3

0/PL 1.15 12.7 1.56 18.2

0/Legume-PL 1.27 14.1 1.61 20.6

0/Rye-PL 1.39 16.0 1.59 19.1

0/Leg-Rye-PL 1.52 17.1 1.73 20.4

LSD(0.05) 0.22 0.29

Total soil N and C content 0- to 5-cm, fall 2016

Corn row vs. inter-row

CoverCrop/PL

Whole plant (stover plus grain) N content, kg/ha

CC 2013* 2014 2015 2016** Ave

Legume 43 71 107 75 74

Legume PL

56 95 138 78 92

Rye 25 48 64 46 46

Rye PL 25 53 80 54 53

LegRye 52 62 97 61 68

LegRyePL 36 68 118 83 76

WF 43 54 88 55 60

WFPL 35 50 69 57 53

LSD(0.05) 27 21 28 17*Grain N content only**Hairy vetch infested with root rot (Phytophthora sp.)

4. Corn N Content

CoverCrop/PL

Fertilizer N Equivalents based on grain yield, kg/ha

CC 2013 2014 2015 2016** 2017 Ave

Legume 6.7 32.9 59.2 41.1 53 38.6

Legume PL

25.4 85.2 117.3 87.1 78 78.6

Rye -27.6 -30.6 -24.4 -5 -14 -20

Rye PL -29.3 -26.8 -5.8 2.6 11 -9.7

LegRye 26.2 -2.9 36.8 13 29 20.4

LegRyePL -12.5 2.5 77.9 35 49.5 30.5

WFPL -4.2 -17.6 -5.5 4 13 2.1

LSD(0.05) 47.3 36.9 50.5

Grain yield based fertilizer N equivalence

*Hairy vetch infested with root rot (Phytophthora sp.)

Year2013 2014 2015 2016 2017

Gra

in Y

ield

, Mg

ha-1

0

2

4

6

8

10

12

14

0 56 112 168 224 Leg LegPL Rye RyePL LegRye LegRyePL PL

5. Grain yield trends

Other Benefits such as wildlife and pollinators

Summary1. Cover crops can be used to increase soil biological

activity.2. Cover crops increased soil organic matter.3. Fall applied poultry litter in combination with legume

cover crops resulted in the greatest nutrient cycling and corn yield.